Recently, attentions have been paid to ink jet systems, i.e., image recording methods in which droplets of recording liquids are discharged from recording heads to record images on recording media, because the running cost thereof is low and this system can be easily applied to color image system for output devices of information instruments such as computers. As recording liquids for ink jet printers, aqueous solutions of dyes which are mainly composed of water and dyes have hitherto been used. However, there is the problem that when recording liquids jetted from nozzles adhere to recording paper, they blurred on the recording paper so that the resulting dot images become extremely larger droplets formed by jetting, or have low image density, to thereby result in low image quality. Further, there is the problem that the images are easily blurred or flow with water, because of low water resistance of the recorded images. Furthermore, there is the problem that the images are easily faded by irradiation of light such as sunlight, because of low light resistance.
As to recording liquids for ink jet printers, techniques have been proposed in which film-forming fine resin particles are added to recording liquids to solve the above described problems of the aqueous solutions of dyes. For example, JP-B-60-32663 (the term "JP-B" as used herein means an "examined Japanese patent publication") discloses a recording liquid to which a latex is added as the fine resin particles, JP-A-5-239392 (the term "JP-A" as used herein means an "unexamined published Japanese patent application) discloses a recording liquid to which a water-dispersible resin having carboxyl and nonionic hydrophilic groups is added, JP-A-5-255628 discloses a recording liquid to which a vinyl polymer of a non-crosslinked structure, and JP-A-6-340835 discloses a recording liquid to which polyester particles having ionic groups are added. Further, JP-B-7-47355 discloses a technique which comprises adding particles of a resin such as a polyester and a crosslinking agent to a recording liquid, and crosslinking the resin on a recording medium.
However, in all of the recording liquids disclosed in the above described patents, film formation of the fine resin particles is initiated at discharge outlet sections of recording heads as water contained in the recording liquids is evaporated by contacting with air. This results in occurrence of clogging. It has been therefore impossible to stably discharge the recording liquids. Further, according to these recording liquids, it has been impossible to completely prevent the recording liquids from blurring in fibers of recording paper by capillary action, to thereby fail to provide images of high image quality. Furthermore, it has been impossible to completely prevent these recording liquids from penetrating into the inside of the recording paper, which imposes a limitation on the acquisition of images of high density and high image quality. Similarly, there is also a limitation on water resistance. Moreover, the dilution of the above described conventional recording liquids with water for avoiding the clogging at discharge outlets decreases the content of fine resin particles contained in the same volume of droplets, namely the content of resin solids contributing to image formation, as compared to that prior to the dilution, which causes a remarkable reduction in image density. It has been therefore impossible to provide images of high image quality. That is, in the conventional recording liquids, the provision of images having a high image density and high image quality by increasing the content of fine resin particles (the content of resin solids) has been incompatible with the avoidance of the clogging at discharge outlets.